A couple of months ago, H+ Magazine had an article on quadcopters, which I really didn’t pay much attention to. It was a neat toy but I skimmed the article, and stuck it away in the back of my head as “interesting, but not important.”
I was wrong. You see, quadcopters have the potential to “change everything” in a major paradigm shift, if properly developed.
If you’re unfamiliar with the quadrotor concept, it’s actually quite simple. With four rotating fans, you can build a helicopter that doesn’t need a tail stabilizer, because each diagonal pair of blades rotates in the opposite direction, eliminating all the rotational force on the vehicle. This produces a stable platform. And moving this platform is easy. Just tilt the blades very slightly, and it can move in any direction. The biggest advantage this system has over a normal helicopter is the fact that the blades don’t have to be movable. A normal helicopter has blades that can be tilted up or down to vary lift. They have very complex joints at the hub of the blade, which makes the blades hard to make, hard to maintain, and very dangerous should any failure occur.
A quadcopter, on the other hand. can make do with very simple, fixed blades, like those on a plane, and unlike a helicopter, those blades can be “ducted”, that is surrounded by a cage structure. If you watched Avatar those small aircraft were actually quadcopters, using dual counter rotating blades in the two side fans as opposed to the more stable four separate rotors. This “fixed blade” makes them inherently safer to operate, both from a materials stress standpoint, and human safety standpoint.
What really got me to looking and thinking about quadcopters differently is this pair of videos.
And just now, I found a third when I was looking up the links
Scary huh?
Watching that little copter slip through openings the size of an air duct or an open window, or “landing” upside down with such high precision might seem scary. Except it isn’t, really. In fact, far from it. It’s actually a potentially great and necessary development, because that last video just illustrated exactly why quadcopters could become as common as cellphones.
Some of you will likely say: “Surely the military isn’t going to be spying on us that much!” No. It’s not the military that’s going to be using them. You will.
How? As a Remote Telepresence Unit, or RTU.
A while back I wrote about VR, and how likely it is that we will have “smartphones” that are linked to a HUD in a pair of lightweight video lenses to enable “good enough VR” through Audio/Visual immersion. This would enable you to interact with both the real and the virtual world in any setting, with any level of immersion you wish. I also talked about how such VR could be used to allow you to travel anywhere in the world as a VR person.
Now, imagine if that “remote you” is a quadcopter equipped with binocular cameras and stereo microphones. Imagine logging into a “local drone hanger” anywhere in the world, and having instant A/V “presence” there. Imagine your “drone” being programmed to stay at your precise eye level; and to maintain as steady a platform as it can; feeding what it sees and hears to you anywhere in the world. And now, imagine that your “remote” is also transmitting a signal that can be picked up by any smartphone VR, so that when someone looks at your “drone” they see a computer generated “Avatar” of you instead of the drone.
Welcome to the world of the RTU.
With the advances being made in battery technology, a fuel cell powered drone could run for days. And with the advances being made in noise cancelling “stealth” technology, if it can silence a full sized copter, it should be able to eliminate the “buzz” from the fans on a drone. Inside of five years, a small, silent, RTU could be feasible. Properly constructed, it could be rugged, cheap, and safe enough to use in any human environment. As a telepresence unit, it could make a Surrogates-like world possible.
But that is not all a quadrotor can do. As you saw in the videos, they can also be enabled with “grippers”, or other “robotic limbs”
So imagine a larger “drone” with a pair of arms, installing steel girders at the top of a high rise, operated by a pilot on the ground in a control room, using his skills remotely and in perfect safety. Imagine a fireman maneuvering a heavy duty drone hauling a firehose into a burning building. Imagine a security guard making his rounds while still guarding the entrance. Or imagine a search and rescue team being able to safely descend into a cave to determine the best method of rescue or a police officer defusing a bomb, remotely and safely. Imagine a movie director with a horde of camera drones able to take a shot from a hundred directions at once. Or a warehouse with hundreds of drones run by just a few dozen people.
Quadcopter drones are already being tested by police and security forces. Google is looking to them to provide low-level aerial photos for their Google Earth program. The drones would be a massive boon to scientists as well. Small drones would enable non-disruptive observation platforms for nearly every environmental and anthropological science. Imagine a solar powered drone programmed to follow a wolf pack, or to investigate the upper levels of a rainforest. Imagine tiny drones able to follow the daily life of a bee or a humming bird.
And yes, we will certainly see many military uses for drones as well, from UAV recon craft to human piloted RTU “Soldier bots” that could perform nearly every function of ground based troop, while keeping a human safely out of harm’s way. Such an RTU would also be impervious to many of the “improvised” weapons that have cost so many lives on both sides in the Afghan conflict. While there are many who fear that such “drone troops” would make warfare “too easy” by enabling “risk free” combat, we cannot allow such fears to overshadow the usefulness of drones in civilian life.
Will we use quadcopter “drones” as RTUs? There’s no way to know, but the potential needs to be explored, because the technology that will make it possible is already here. In theory, we could take that camera drone (as seen on the video), and modify it into an RTU right now. And that very first video shows that it’s entirely possible to control a quadcopter from a smartphone.
If you still think that it might be dangerous to have rotating blades, especially for small children, talk to Dyson. Maybe that air multiplier could be made strong enough to power a RTU instead, and then you wouldn’t have any exposed fan blades to stick small fingers into.
So, if you’ve ever played a video game where the camera hovers behind you and wished you could do that IRL; or if you’ve ever wanted the ability to “fly your POV around” like you can in Secondlife, then keep your eyes on Quadcopters. If they are developed with the right goals in mind, you just might get your wish.
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And already another update. I was given this video link recently (while talking about the fact that I had written this article over at Imminst)
This has GPS location finding and auto return, height from ground sensors, cameras, and might be more stable than a quad (not sure)
Already we are 70% to 80% of the way to a RTU like I describe above,
I also noticed this in the final video, which shows the “Safety” shields for the blades in place. (It’s only shown setting next to the drone in the video above.)
And another Update:
Brain Wang over at Next Big Future read this article and did his own research into “RTUs”
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IEEE Spectrum covers quadcopters, hexacopter and octocopter UAVs.
According to a recent Robots Podcast interview with Joshua Portlock, manager of the CyberQuad project at Australia’s Cyber Technology, what happened is a classical case of an enabling technology being driven by the consumer market. Fast, precise and affordable accelerometers are a key technology for Quadcopters. Their development was initially driven by their use for airbags in cars, and now increasingly by their use in consumer devices such as mobile phones. Accelerometers are key because unlike standard helicopters, which use complex mechanics to allow stable flight, Quadrotors use fast onboard motor control to take care of stability. This mechanical simplicity is also their main attraction: Quadrotors can navigate in three dimensions using only four moving parts. And the high reliability of brushless motors makes them a simpler, more reliable alternative to many traditional flying platforms. Hexacopters pack more rotors into a given size to provide more power.
Quad vs Hexa vs Octo -copter Advantages-Disadvantages
General rules (from Martin Seven) are that more engines means more power and more lift. That means more batteries. That means more time in the air. Brushless electrics like to run slow (lower RPMs), so bigger means more efficient. If efficiency is your goal, coaxial = evil (radial is more efficient).
The breakdown
Tricopters: cheap, easy to build, least stable, not as robust (tail servo and mechanics), low lifting power and flight time (because the motors have to run faster to hold it all in the air). No engine out capability.
Quadcopters: mechanically simpler than tris. While they weigh almost the same they have about 1/3 more lift, they are usually more stable (no servo issues) and are capable of staying airborne for a little while longer (they can either lift larger batteries or fly more economically because the weight is spread across 4 motors and not just 3). Still no engine out capability. If it fails, it goes down.
Hexacopters: All the good things that quads have, plus more power and more lifting capability. As a bonus they add limited engine out capability – a hexacopter can lose any single engine and still land (it will lose yaw control though), and if it loses one or both engines on the neutral torque bar it could even continue flying unaffected. Downside is that they are larger and a little pricier, especially if you’re running high-grade motors like AXI.
Octocopters and heavier: All the good things from hexacopters, plus true engine out ability. Loses any single one and still flies fine. This is what you fly if you need horsepower and reliability in one package. This is what you strap that $1300 Canon 7D under. Even more expensive though. Also heavy craft are really power hungry and unless you have some serious chargers at hand they require a lot of work on the ground before a flight can be made (charging say 5 packs for 25 minutes in the air).
Re more motors and velocity/maneuverability – that depends. It depends on the weight-to-lift ratio. If your machine weighs say 2 kg and each of your 4 motors gives out 625 g of thrust (4*.625 = 2.5 kg), then you have a ratio of 2.5/2 = 1.25, which is not really good. However, if your quad weighs 2 kg and each motor maxes out at 1 kg of thrust (4 kg total), then you’re looking at a lift-to-weight ratio of 4:1, which means plenty of power and speed for acrobatics.
If you have more motors you have to consider the battery ratings: a 5000 mAh 20C battery has a max current of 5*20 = 100 A. If you have eight motors and each can draw up to 17 A (136 A total), then you either need to use a stronger battery (or more of them in parallel) or limit the engines in software using a current monitor.
Lithium Polymer batteries currently have up to 200 watt hours per kilogram. In future, Lithium-metal batteries approach the energy density of fuel cells without the plumbing needed for these devices; in theory, the maximum energy density is more than 5,000 watt-hours per kilogram, or more than 10 times that of today’s lithium-ion batteries.
1000 watt hours per kilogram lithium batteries are expected in mid-2011
So 5-25 times better performance than lithium polymer is possible.
And let’s update this again:
A quadcopter connected to a Kinect for autonomous flight.
Now set things up to transmit the binocular camera feeds to a set of lenses, while using the lidar to control the drone’s height and collision avoidance, and what do you have?
Oh yeah, a basic RTU.
and another new video showing how quickly improvements are being made
Yes, the drone is juggling at least as well as I can (which is more a testament to my lack of juggling skills than anything else XDDDDD )